The present invention relates to an antenna assembly suitable for wireless transmission of analog and/or digital data, and more particularly to a dual frequency, wideband radiator.
There are a variety of antennas which are currently used in wireless communication devices. One type of antenna is an external half wave single or multi-band dipole. This antenna typically extends or is extensible from the body of a wireless communication device in a linear fashion. Because of the physical configuration of this type of antenna, electromagnetic waves radiate equally toward and away from a user. Thus, there is essentially no front to back ratio and little or no specific absorption rate (SAR) reduction. Specific absorption rates for this type of antenna are typically 2.7 mw/g at a 0.5 watt transmission power level. With multi-band versions of this type of antenna, resonances are achieved through the use of inductor-capacitor (LC) traps. With this antenna, gains of +2 dBi are common. While this type of antenna is acceptable in some wireless communication devices, it has drawbacks. One significant drawback is that the antenna is external to the body of the communication device. This places the antenna in an exposed position where it may be accidentally or deliberately damaged.
A related antenna is an external quarter wave single or multi-band asymmetric wire dipole. This antenna operates much like the aforementioned antenna, but requires an additional quarter wave conductor to produce additional resonances. This type of antenna has drawbacks similar to the aforementioned antenna.
Another type of antenna is a patch antenna. The patch antenna is a small, low profile antenna which is useful in wireless communication devices. They typically have operating bandwidths (2:1 VSWR) on the order of a few percent. The operating bandwidth may be increased by adding parasitic elements. However, the total size of the antenna increases proportionately. The front to back ratio is usually poor unless the ground plane size is also increased. Thus, in creating a patch antenna with a relatively large bandwidth, the primary advantage of the patch antenna is defeated.
There exists a need for an antenna assembly which is compact and lightweight. There is also a need for an antenna assembly which is able to receive and transmit electromagnetic frequencies at one or more frequency bands. There is a need for an antenna assembly with a reduced specific absorption rate. There is also a need for an antenna assembly which can be tuned to one or more frequency bands.
A dual frequency wideband antenna assembly for use in a wireless communication device. The antenna assembly includes first and second conductive surfaces, each having a first arm and a second arm which define a notch. The first and second conductive surfaces are in substantial collateral relation and include a dielectric member interposed therebetween in a laminar fashion. A conducting element operatively connects the first and second conductive surfaces to each other along predetermined edges, respectively. The first arms of the first and second conductive surfaces and a portion of the conducting element comprise a first radiating element, and the second arms of the first and second conductive surfaces and another portion of the conducting element comprise a second radiating element. In one embodiment, the first and second radiating elements are effectively operable over the ranges of 880-960 MHz and 1710-1880 MHz, respectively. The antenna assembly is spaced a predetermined distance from the ground plane of a printed wiring board, and is operatively connected thereto at several predetermined locations by several components. One component, a capacitor, operatively connects an end of one of the arms of first radiating element to a ground plane. Another component, a feed element, operatively connects the second radiating element to the signal conductor of the device. And, a third component, a grounding element, operatively connects the second radiating element to the ground plane. Since the distance between the antenna assembly and the ground plane is a function of the particular wavelengths used, the space between the antenna assembly and the ground plane may vary. However, it will be appreciated that various componentry may be positioned within the open space(s) between the antenna assembly and the ground plane to facilitate compact construction. The antenna assembly so constructed, provides a two-to-one voltage standing wave ratio with bandwidths of around 15 percent that has a low specific absorption rate and is particularly useful in wireless communication devices such as cellular telephones.
It is an object of the present invention to provide an antenna assembly which may be incorporated into a wireless communication device.
It is an object of the present invention to enhance operation of an antenna assembly by increasing its operational bandwidths.
It is an object of the present invention to increase the operational parameters of a wireless communication device by providing two or more complimentary radiating elements.
A feature of the present invention is that the radiating elements of the antenna assembly are tunable over a range of frequencies.
Another feature of the present invention is that there is a single feed point for multiple electromagnetic frequency bands.
An advantage of the present invention is that the antenna assembly has a low profile which enables it to be used in small articles such as wireless communication devices.
Another advantage of the present invention is that various components of a transceiver device may be positioned within interior regions of the antenna assembly to reduce the overall size of the electronic device.
These and other objects, features and advantages will become apparent in light of the following detailed description of the preferred embodiments in connection with the drawings.